Spray drying offers an opportunity to control the particle size of an inorganic support and a supported catalyst, which in turn is used to control particle size and final polymer product properties in gas phase polymerization. Silica, a favorite catalyst support, is typically spray dried to obtain certain ranges of particle sizes and distributions. Similarly, catalyst systems themselves are spray-dried. For example, U.S. Pat. No. 4,424,138 discloses a solution having a solid component, an agglomeration enhancer of dissolved polystyrene and other components spray dried for use as a polymerization catalyst in gas phase.
It is also known that polymers can be used as catalyst supports since they are less susceptible to typical catalyst killing impurities such as, for example, water and oxygen. Supported porous polymer particles having pore sizes of 10 angstroms are disclosed as supports in U.S. Pat. No. 5,118,648. (See also U.S. Pat. No. 5,051,484 and U.S. Pat. No. 4,921,825 for polymeric supports.) These "spongy" polymeric supports, however, do not provide uniform pore sizes, which in turn can lead to reactor fouling and other undesired events.
There has been a need for a method to produce small particle size organic polymer supports having good pore size distribution for use as catalyst supports.